Wagner guided Huddersfield into the top flight in 2016-17 for the first time in 45 years after winning the Championship playoff final against Reading. With the odds stacked against him, he then kept them in the top flight last season.

This campaign has been more difficult, however, with Huddersfield winning two of their 23 matches and currently sitting 10 points adrift of safety at the bottom of the table.

Siewert has previously coached Germany's international youth sides and held senior management roles at VfL Bochum and Rot-Weiss Essen apart from his role in charge of Dortmund II.

"Jan's name came to our attention in his previous role as assistant manager and under-19 Coach at VfL Bochum," Town's chairman Dean Hoyle told the club's official website. "We first spoke with him over two years ago and we've kept in communication since, watching his progress with interest."

Hoyle also said that Siewert had been tasked with enhancing the high-pressing identity that Wagner had instilled in the team, while his reputation for promoting youth had also made him an attractive candidate.

"Many of [Siewert's] core philosophies and beliefs about how he wants his teams to play match our own," Hoyle said. "He likes high-effort, high-intensity, high-pressing football that is good to watch.

"In the short-term, we will continue to fight as hard as possible against relegation from the Premier League. We're not giving up on that.